Solar radiation simulation experiments

The kinetics of the various reactions have been explored in detail using large-volume chambers that can be used to simulate reactions in the troposphere. They have frequently used hydroxyl radicals formed by photolysis of methyl (or ethyl) nitrite, with the addition of NO to inhibit photolysis of NO2. This would result in the formation of 0( P) atoms, and subsequent reaction with Oj would produce ozone, and hence NO3 radicals from NOj. Nitrate radicals are produced by the thermal decomposition of NjOj, and in experiments with O3, a scavenger for hydroxyl radicals is added. Details of the different experimental procedures for the measurement of absolute and relative rates have been summarized, and attention drawn to the often considerable spread of values for experiments carried out at room temperature (-298 K) (Atkinson 1986). It should be emphasized that in the real troposphere, both the rates—and possibly the products—of transformation will be determined by seasonal differences both in temperature and the intensity of solar radiation. These are determined both by latitude and altitude. 

Principles of simulation have been elaborated by Carpetis [22] who introduced the current-voltage characteristic of the solar cell in an implicit form, O (I, Vj, T, J) = 0 where Ig and Vg are the cell output photocurrent and voltage respectively, T is the cell temperature, and J is the solar radiation intensity. Besides four variables the function O contains also five constants which are to be determined from five independent sets of experiments. 

A Pyrex glass bottle of 50-mL capacity was used as batch reactor. In these flasks 40 mL of water was the total volume. Solar irradiation was simulated by a Hanau Suntest (AMI) lamp. Total radiation measurements were carried out with an YSI corporation power meter. Experiments were performed at room temperature (25°C) reaching up to 32°C during irradiation. 

R.D. Hurtubise, J.E. Havel, E.E. Little (1998). The effects of ultraviolet-B radiation on freshwater invertebrates Experiments with a solar simulator. Limnol Oceanogr., 43, 1082-1088. 

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